Background Optical coherence tomography (OCT), a high resolution intravascular imaging technique, requires blood displacement for reliable image acquisition and the current technique uses a soft occlusion balloon plus saline injection in the coronary artery. A non-occlusive technique based on manual infusion of a viscous iso-osmolar solution has been developed and tested and validated through a 2-phase study. Methods and Results OCT assessment was performed with the M2 LightLab OCT (LightLab Imaging, Westford, MA, USA) image-wire in 3 swine by infusing 30 ml of each of 3 solutions differing in viscosity, osmolarity and electrolytic composition (A: iodixanol 320 and Lactated Ringer ...